Katherine
We've all had some shit circumstances in our lives. My parents were insane and hunted my family for a thousand years, you lost a child and later your family. Circumstances made us what we are, but we admit it. I was going to dagger Kol myself, that would have ended the compulsion on Damon and saved Jeremy. But what she did was the fast route to getting the mark done, she murdered my brother and tens of thousands of vampires for her own gains, making her even worse than us.
Bo is the best of us, she's an amazing little girl.